Production process for hydraulic binder-based boards with four tapered edges, production line of such boards

Abstract

A production process is provided for a board of hydraulic binder with a facing on each of its sides. The process includes on one side first tapered parallel edges and on the same side or the other side, two second tapered parallel edges perpendicular to the first. The process also includes the use of a forming lath having at least two distal parts. The process can be used in a production line that includes a specific lath.

1. A production process for a board of hydraulic binder, the process comprising:
 1) pouring a hydraulic binder slurry on a first facing material supported by a conveyor belt and at least two longitudinal forming strips, and covering the hydraulic binder slurry with a second facing material so as to obtain a preform; 
 2) producing an imprint in an upper part or a lower part of the preform using at least one lath having at least two distal parts and comprising a plurality of bars embedded in a polymer matrix at the level of the distal parts; the lath being withdrawn before hydraulic setting begins; 
 3) allowing for hydraulic setting of the hydraulic binder slurry to take place; and 
 4) cutting the preform at a level of a tapered section created by the imprint into the board of hydraulic binder with the facing materials on each of its sides, the board comprising on one side two first tapered parallel edges and on the one side or another side two second tapered parallel edges perpendicular to the first. 
 
     
     
       2. The production process according to  claim 1 , wherein the imprint is made by introducing the lath to the preform before a forming plate device. 
     
     
       3. The production process according to  claim 1 , wherein the imprint is made on the lower part of the preform. 
     
     
       4. The production process according to  claim 1 , wherein the imprint is made on the upper part of the preform. 
     
     
       5. The production process according to  claim 1 , wherein the bars are flat with a shape ratio comprised from 10:1 to 3:1. 
     
     
       6. The production process according to  claim 1 , wherein the two distal parts are separated by a central part, the central part representing 20 to 90% of a total width of the lath. 
     
     
       7. The production process according to  claim 1 , wherein the two distal parts are separated by a central part comprising a plurality of recesses. 
     
     
       8. The production process according to  claim 7 , wherein the recesses have a width comprised from 4 to 12 mm, a length comprised from 8 to 20 mm and a space between the recesses comprised from 15 to 30 mm. 
     
     
       9. The production process according to  claim 1 , wherein the hydraulic binder comprises gypsum. 
     
     
       10. The process according to  claim 4 , wherein in the board, the two second tapered parallel edges are transverse. 
     
     
       11. The process according to  claim 1 , wherein the board further comprises two third tapered edges parallel to the two second tapered edges, on a side of the board other than the side comprising the two second tapered edges. 
     
     
       12. The process according to  claim 1 , wherein in the board, the two second tapered parallel edges have a width comprised from 100 to 200 mm. 
     
     
       13. The process according to  claim 1 , wherein in the board, the depth ratio of the two second tapered edges to the depth of the two third tapered edges is comprised from 1 to 10. 
     
     
       14. The process according to  claim 13 , wherein in the board, the width of the two second tapered parallel edges is comprised from at least one of 120 to 180 mm, 150 to 200 mm, and 100 to 150 mm. 
     
     
       15. The process according to  claim 1 , wherein in the board, the two first and two second tapered parallel edges are approximately of equal width. 
     
     
       16. The process according to  claim 1 , wherein in the board, the two second tapered parallel edges have a width such that a width ratio of the two second tapered parallel edges to a width of the two first tapered parallel edges is comprised from 1.5 to 5. 
     
     
       17. A production line for hydraulic binder-based boards from a preform, the preform comprising a facing material covered with a hydraulic binder slurry and supported by a conveyor belt comprising a longitudinal forming strip, the preform further including a second facing material on an upper part thereof; the production line further comprising a device forming an imprint on the preform before the imprint encounters the forming strip, the imprint being made on the upper part of the preform, wherein the imprint-forming device comprises:
 a frame; 
 two first pulleys supported at a first end of the frame and two second pulleys supported at a second end of the frame opposing the first end of the frame; the first pulleys and second pulleys being in parallel planes; the pulleys opposite one another being identical; 
 two drive belts encircling respectively the first pulleys and the second pulleys; and 
 at least one lath attached in a removable manner to the belts and extended between the belts in such a way that a longitudinal axis of the at least one lath is parallel to a rotation axis of the pulleys, 
 the lath having at least two distal parts; and 
 a distance between the drive belts of the imprint-forming device being at least equal to a width of the preform, and the imprint-forming device being arranged in a manner so that when the drive belts turn, the lath creates an imprint in the preform. 
 
     
     
       18. The production line according to  claim 17 , further comprising upper and lower forming plates, between which the lath can pass. 
     
     
       19. The production line according to  claim 17 , wherein the hydraulic binder comprises gypsum. 
     
     
       20. The production line according to  claim 17 , wherein the lath comprises a plurality of bars embedded in a polymer matrix in the distal parts. 
     
     
       21. The production line according to  claim 20 , wherein the bars are flat with a shape ratio comprised from 10:1 to 3:1. 
     
     
       22. The production line according to  claim 17 , wherein the lath comprises two distal parts separated by a central part, the central part representing 20 to 90% of a total width of the lath. 
     
     
       23. The production line according to  claim 17 , wherein the two distal parts of the lath are separated by a central part comprising a plurality of recesses. 
     
     
       24. The production line according to  claim 23 , wherein the recesses have a width comprised from 4 to 12 mm, a length comprised from 8 to 20 mm and a space between the recesses comprised from 15 to 30 mm. 
     
     
       25. A production process for a board of hydraulic binder with a facing on each of its sides, the board comprising on one side two first tapered parallel edges and on another side two second tapered parallel edges perpendicular to the first, the process using a production line according to  claim 17 .